Season the pork all over with the salt and pepper. Place it in the slow-cooker. Pour 3 c. of the barbecue sauce on the roast, cover, and cook on either low for 8-10 hours or on high for 6-8 hours, until roast is falling apart.

Transfer the meat to a large bowl and let cool slightly. Skim the fat off of the cooking liquid and mix 1 c. cooking liquid with the reserved barbecue sauce (use 1/2c - 1c, depending on your preference). Add 2 - 3 T. cider vinegar if you would like a vinegar based sauce, and the liquid smoke if you would like a smoky flavor. Add salt and pepper to taste to the sauce.

When the meat is cool enough to handle, shred it by hand, discarding fat and gristle. Toss the shredded meat with the sauce, 1c. at a time. Serve.